Hi Pat,
My M2A1, until my rebuild, had its fire extinguisher in the original location mounted on the passenger side firewall. It fit right in the middle of where the later air cleaner comes through. On the air cleaner you can select where you want the air to be pulled from, engine compartment or inside under the dash for cold weather. I never had a problem with the fire extinguisher interfering with the air cleaner performance. I now have a later CO2 extinguisher mounted on the passenger door.
Steve A.